Directed differentiation of skin-derived precursors into functional vascular smooth muscle cells.

Objective: The goal of this study was to characterize the factors and conditions required for smooth muscle cell (SMC)-directed differentiation of Sox2(+) multipotent rat and human skin-derived precursors (SKPs) and to define whether they represent a source of fully functional vascular SMCs for applications in vivo.

Methods And Results: We found that rat SKPs can differentiate almost exclusively into SMCs by reducing serum concentrations to 0.5% to 2% and plating them at low density. Human SKPs derived from foreskin required the addition of transforming growth factor-β1 or -β3 to differentiate into SMCs, but they did so even in the absence of serum. SMC formation was confirmed by quantitative reverse transcription-polymerase chain reaction, immunocytochemistry, and fluorescence-activated cell sorting, with increased expression of smoothelin-B and little to no expression of telokin or smooth muscle γ-actin, together indicating that SKPs differentiated into vascular rather than visceral SMCs. Rat and human SKP-derived SMCs were able to contract in vitro and also wrap around and support new capillary and larger blood vessel formation in angiogenesis assays in vivo.

Conclusions: SKPs are Sox2(+) progenitors that represent an attainable autologous source of stem cells that can be easily differentiated into functional vascular SMCs in defined serum-free conditions without reprogramming. SKPs represent a clinically viable cell source for potential therapeutic applications in neovascularization.